1. Field of the Invention
This invention relates to organosiloxane compositions that are curable to form organosiloxane elastomers. More particularly this invention relates to organosiloxane compositions that are curable to form organosiloxane elastomers that exhibit extended moldlife.
2. Description of the Related Art
The prior art also describes organosiloxane compositions that cure to yield crosslinked elastomers by the reaction of a polyorganosiloxanes containing at least two alkenyl groups per molecule with organosilicon compounds containing at least three silicon-bonded hydrogen atoms per molecule as the crosslinker. This reaction is typically catalyzed by platinum containing compounds.
In U.S. Pat. No. 4,879,339, which issued on Nov. 7, 1989, Yoshino et al. disclose a composition comprising a vinyl containing organopolysiloxane; an organohydrogenpolysiloxane; a platinum compound; an aliphatic hydrocarbon; and an antioxidant.
In U.S. Pat. No. 4,654,408, which issued on Mar. 31, 1987, Okinoshima discloses a composition comprising vinyl containing organosilicon compound; a platinum compound; and an antioxidant.
Yet another reference is European Patent Publication 0 531 009 A1, which published on Mar. 10, 1993 in the name of Judith stein, in which there is disclosed a silicone release composition comprising a polydiorgansiloxane containing unsaturated groups, a crosslinking agent containing Si-H groups and a hydrosilation catalyst, which release composition also contains at least one free radical inhibitor to prevent "acrylic weld" to acrylic surfaces.
The compositions of the present invention contain a free radical scavenger for radicals that participate in the free radical polymerization of styrene monomers. These free radical scavengers may be antioxidants. The present inventors discovered compositions containing selected free radical scavengers yield elastomers having unexpectedly improved moldlife.